Questions tagged [digital-communications]
Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.
437
questions
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1answer
33 views
About best way to perfom checksum
From my knowledge,checksum can be done using Xor or adding the bytes of the frame...i have to create a communication between ATmega32 microcontroller and matlab to perform some functions...which is ...
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0answers
22 views
Overvoltage and overcurrent protection to digital signal lines
I'm looking for a technology that protects digital signal lines like SPI, I2C, UART and general purpose I/O against overvoltage and short circuit. That is, protects the microcontroller's digital ...
1
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2answers
48 views
Are USB and/or Ethernet payload agnostic?
I'm working on a project in which I'm trying to reduce the number of conductors in a high-bandwidth, multi-signal communication interface that requires a fiber connection for isolation and a back ...
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0answers
54 views
What is the role of R1/C1, R3 in this slicer circuit?
I found the following data slicer circuit:
simulate this circuit – Schematic created using CircuitLab
The input is a simple NRZ (PAM-2) signal between "Vhigh" and "Vlow" (=...
1
vote
2answers
72 views
SSB and Hilbert transform
I have came across a question where it asks if the input to SSB (LSB) modulator is mh(t) (which is the hilbert transform of m(t)), will the of the modulator be LSB?
What I did :
I did the math and ...
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1answer
45 views
MAX7219 Entering Test Mode and Displaying Random Characters
I'm using MAX7219 with 6 common cathode 38mm (each segment has 2 red LEDs except DP) 7-segments controlled by Arduino Mega2560. I have connected MAX7219 and the board as stated in MAX7219's datasheet (...
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0answers
37 views
why sometimes we need to use Broadband Transmission (Using Modulation)?
I was reading a textbook which says:
Baseband transmission requires that we have a low-pass channel, a channel with a bandwidth that starts from zero. This is the case if we have a dedicated medium(...
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1answer
60 views
What are the Electronic Components & Devices for Digital Modulation Formats? [closed]
So I have been searching on google for hours but I found nothing, I want to know what are the Components and Devices for Digital Modulation Formats ?
Our Professor asked us to write a report
The ...
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1answer
19 views
MIMO power output
If local regulations require Wifi's EIRP to be less than 200mW, then for a 4 channel MIMO antenna Wifi tranceiver, will each channel limit the power output to 50mW and each have a 50mW power amplifier?...
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1answer
31 views
Low Power SPI Module communication between Microcontrollers
I have 2 microcontrollers - one is S32K118 and other is S32K142. Both are 64 pins. S32K1xx datasheet
I need communication between the Microcontrollers in SPI Configuration.
Suppose the microcontroller ...
0
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4answers
136 views
What's the benefits to using analog-to-digital conversion like PCM?
I was reading a textbook, Data Communications And Networking, by Behrouz A. Forouzan, which says:
A digital signal is superior to an analog signal. The tendency today is to change an analog signal to ...
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2answers
60 views
Are there any real world examples of encoding data in EM polarization?
Data can be encoded by modulating the frequency, amplitude and phase. But I can't find any references for encoding data in the polarization of EM waves (either analog or digital). This is probably for ...
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1answer
42 views
How does bipolar line coding such as AMI work with medium like fiber optics
We know that in bipolar encoding (sometimes called multilevel binary), there are three voltage levels: positive, negative, and zero. The voltage level for one data element is at zero, while the ...
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0answers
24 views
Bluetooth and Wifi Interference
I have read that bluetooth devices had a built in short range with data rate of 1Mbps with a 2.4 Ghz Frequency, which means that there is possibility of interference between IEEE 802.11b WLANs and ...
0
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1answer
45 views
why a channel needs to have bandwidth requirement for digital data transmission?
I'm not from EE background and try to understand how digital is sent in a channel as a non technical audience.
Let's say we use fiber optics to transmit digital data 010101...., since fiber optics ...
6
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3answers
1k views
Could Cat5e be used for RS485 [duplicate]
I'm working on a project that will be using RS485 to communicate between a bunch of modules and a master controller. Low baud rate, 9600, but a decent distance, like a couple of hundred feet. I'm ...
0
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1answer
46 views
How to tell whether a line coding scheme has DC component or not
I'm new to EE, trying to understand things as a non technical audience.
My textbook says one of bipolar encoding schemes called alternate mark inversion (AMI) has no DC component and we can think ...
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2answers
51 views
Does NRZ-I have a synchronization problem?
I'm new to EE, just have a question on synchronization.
I was reading a book which says:
NRZ-I has no problem with sequences of 1s, but has problem with sequences of 0s.
It certainly has a ...
0
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0answers
18 views
Does Carrier frequency offset (CFO) means difference of the message frequency and integrator?
Can anyone here tell me what is CFO? Initially, I thought it might be when the message signal mi, that is
$$r(t) = 2P cos(2\pi fc*fi+\delta f)$$ doesn't match with integrator $$\int_0^T r(t) * cos((...
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2answers
48 views
Can we get higher internet speeds even with low BW message signals?
Consider a case where i’m listening to a recorded audio on internet.Basically the useful audio Frequency range lies b/w 40hz to 4khz, which has a BW of 4khz which is pretty low ,does that mean the ...
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3answers
53 views
Does data rate depends on Frequency not on BW?
If we have two RF signals of 900Mhz and 1800Mhz both of equal Bandwidth 20Mhz which one has higher data rate?
0
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1answer
30 views
Understanding OSI Communication Model in Hardware
I have gone through the OSI communication model and the associated levels.
But I do not understand on how is this implemented in the Hardware level. Or let me put it like this.
Suppose we have a ...
2
votes
1answer
64 views
Beginner trying to learn how to read start and end addresses for memory chips in hexadecimal
I'm new to electrical (construction management student) and am trying to learn how to read start and end addresses. The practice problem I have been given is in the picture, and I was wondering how I ...
0
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2answers
38 views
What is meant by downstream bandwidth in lte?
In my phone, it says that the downstream bandwidth of LTE is 10Mhz. But if a carrier frequency of 900Mhz has a bandwidth of 20Mhz, i.e., frequency ranges from 900Mhz to 920Mhz, then I have almost half ...
0
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1answer
38 views
What is the relation between bandwidth and data rate?
If I have a 20Mhz bandwidth provided by my 2.4ghz router then will my internet speed will be 20M symbols per sec which is equal to 20×4= 80Mbps (considering 16 qam modulator with 4 bits per symbol)
Is ...
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vote
2answers
67 views
How do we separate source signals in spread spectrum?
In a point-to-point mode, that is, one transmitter and one receiver, I understand how a spread spectrum receiver can read the transmitted signal from a spread spectrum transmitter by knowing the code. ...
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2answers
41 views
Effective differences between MAX485EESA+T and MAX485ESA+T?
Is anyone able to explain to me the effective difference between the MAX485EESA+T and the MAX485ESA+T?
The datasheet points out that is more tolerant of ESD discharge up to 15kV, nothing more.
Can ...
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votes
2answers
116 views
what factor (in dB) is the output SNR or signal power affected by this phase error?
In a BPSK system, if at the receiver the oscillator has a phase error of phi =40° i.e. you are
multiplying the received signal with an appropriate cosine signal phase shifted by 40°. Then,
after low ...
0
votes
3answers
78 views
Probability of error of a system?
Let bits 0 and 1 be equi probable. For bit 0, any value between -0.3 V and 0.3 V can be taken
with equal probability. Similarly for bit 1, any value between 0 V and 1 V can be taken with
equal ...
1
vote
1answer
35 views
How to plot BER Vs SNR of a received signal
I am using USRP to transmit and received MIMO frames similar to Wi-Fi standard that I created on my own. After receiving the signal, it is processed as described in the standard.
While I plot the ...
0
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1answer
53 views
What limits the maximum number of nodes of a RS422 bus? How to check if N>10 nodes is possible without repeater?
I have 13 identical devices which communicate with a host via RS422. None of them are addressable (they assume point-to-point connection).
I would like to string them in a RS422 bus. I thought of ...
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1answer
22 views
Coded OFDM, interleaving, sensitivity, and narrow band interference
Coding (which is a controlled redundancy) and interleaving across sub-carriers protects OFDM signals from a narrow band interferer (CW) that could destroy one subcarrrier. It provides a kind of ...
0
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2answers
26 views
Truncation noise in digital circuits
I was reading a chapter of my book (I am not putting it as reference since it is not in english) about the quantization noise problem in digital filters. Specifically, it writes about a filter that ...
2
votes
2answers
137 views
Doubts about IIR filters definition and transfer function
I have some basic doubts about IIR digital filters.
My first question is about its definition. IIR means Infinite impulse response, so my question is: is it physically possible to realize such ...
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0answers
27 views
How do I write a requirement of an asynchronous input signal, when the sampling clock has a certain resolution?
Let's say I have an asynchronous input (let's call it enable_h). This signal is supposed to be active high for 100us.
My 2mhz clock is double-registering this async input. So once it is in my clock ...
2
votes
2answers
76 views
What is the meaning of Angular Velocity Vector 100Hz of BNO055?
I am using an Arduino Nano with BNO055 Adafruit library.
The I2C speed is 400 kHz.
The Adafruit BNO055 Absolute Orientation Sensor mentions Angular Velocity Vector (100 Hz).
What does this 100 Hz ...
0
votes
2answers
36 views
Where do we use arithmetic multipliers in 5G technology?
I have recently learned about arithmetic multiplication and the various types of multipliers used in digital circuit design. Now, having an interest in cellular technology, I am curious about the ...
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2answers
32 views
Filter ripples and their effect on signal quality
Ripples cause an amplitude distortion in addition to a phase distortion expressed in terms of RMS phase deviation (from linear) or group delay variation over a certain signal bandwidth.
The question ...
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1answer
41 views
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0answers
23 views
Component Connection Protocols
I am trying to understand what the Data Stream coming through the Component Wires when they are used to connect to a Monitor from a DVD/BLURAY player, Hauppaugge or whatever. Is there a set of IEEE ...
0
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1answer
71 views
USB to RS485: Can I connect A to Common Ground?
I bought a very cheap USB to RS485 dongle to connect to an experimental board of my own.
Specifications (may differ from the one I used but externally similar):
- Any baud rate from 1200 bps to 115 ...
0
votes
1answer
22 views
Time Auto-correlation function for a polar reutrn-to-zero waveform
I used matlab to calculate the time Auto-correlation function for a polar return-to-zero waveform
to make sure that it has an ergodic property . I implemented the following formula as a function in ...
0
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1answer
66 views
How could a digital multiplexer transmit at a rate higher than its input?
From Wikipedia, "a multiplexer, also known as data selector, is a device that selects between several analog or digital inputs and forwards it to a single output line."
https://en.wikipedia.org/wiki/...
0
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1answer
39 views
Is time-division multiplexing really a multiplexing method or more of a protocol?
If my understanding is correct, when we are multiplexing, the stations are not supposed to be aware of the multiplexing.
For example, if we have computers 1, 2, 3, & 4 talking to computers a, b,...
3
votes
2answers
81 views
Do we use any filter after photodiode?
In wireless communication, we use a matched filter to suppress out-of-signal-space noise. After this filtering we do sampling. Otherwise, the power of noise is infinite (practically very large).
In ...
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4answers
83 views
What is the exact difference between synchronous and asynchronous serial transmission?
I'm having a hard time understanding the exact distinction between synchronous and asynchronous serial because different sources have confusing description.
For example, some source say a separate ...
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1answer
79 views
Troubleshooting periodic noise in raw data collected from ADC
We are working on an ADC that has maximum sampling rate of 2.5MSps at clock frequency of 40MHz and Vref of 2.5V. The architecture is SAR and it carries out the calibration internally.
Currently we ...
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3answers
39 views
Power spectra density for line code
Why do we need to find power spectra of different line codes? why we relate it to to the auto correlation of the signal? how does it help us in transmission of digital signals?
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2answers
110 views
Level shifter vs pull up resistor
I was thinking today and am curious, assuming there is an open collector output on two chips, one that runs on 3.3V and cannot tolerate 5.0V, and a 5.0V chip, could they just communicate by using ...
0
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0answers
26 views
Ripple effect on EVM
I am trying to find an analysis that would show the impact of filter ripple on the signal quality of a signal (EVM or RHO) . Does any one know of an existing analysis in a paper, a book or a website?
